Re: [Intel-gfx] [PATCH v5 1/6] drm/i915: Call i915_gem_evict_vm in vm_fault_gtt to prevent new ENOSPC errors, v2.

[Thomas Hellström]

On 1/13/22 12:44, Maarten Lankhorst wrote:

Now that we cannot unbind kill the currently locked object directly
because we're removing short term pinning, we may have to unbind the
object from gtt manually, using a i915_gem_evict_vm() call.

Changes since v1:
- Remove -ENOSPC warning, can still happen with concurrent mmaps
   where we can't unbind the other mmap because of the lock held.
   This  fixes the gem_mmap_gtt@cpuset tests.

Signed-off-by: Maarten Lankhorst <maarten.lankho...@linux.intel.com>

Reviewed-by: Thomas Hellström <thomas.hellst...@linux.intel.com>

---
  drivers/gpu/drm/i915/gem/i915_gem_mman.c | 18 ++++++++++++++++--
  1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c 
b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
index 5ac2506f4ee8..fafd158e5313 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
@@ -21,6 +21,7 @@
  #include "i915_trace.h"
  #include "i915_user_extensions.h"
  #include "i915_gem_ttm.h"
+#include "i915_gem_evict.h"
  #include "i915_vma.h"

static inline bool

@@ -358,8 +359,21 @@ static vm_fault_t vm_fault_gtt(struct vm_fault *vmf)
                        vma = i915_gem_object_ggtt_pin_ww(obj, &ww, &view, 0, 
0, flags);
                }

- /* The entire mappable GGTT is pinned? Unexpected! */

-               GEM_BUG_ON(vma == ERR_PTR(-ENOSPC));
+               /*
+                * The entire mappable GGTT is pinned? Unexpected!
+                * Try to evict the object we locked too, as normally we skip it
+                * due to lack of short term pinning inside execbuf.
+                */
+               if (vma == ERR_PTR(-ENOSPC)) {
+                       ret = mutex_lock_interruptible(&ggtt->vm.mutex);
+                       if (!ret) {
+                               ret = i915_gem_evict_vm(&ggtt->vm);
+                               mutex_unlock(&ggtt->vm.mutex);
+                       }
+                       if (ret)
+                               goto err_reset;
+                       vma = i915_gem_object_ggtt_pin_ww(obj, &ww, &view, 0, 
0, flags);
+               }
        }
        if (IS_ERR(vma)) {
                ret = PTR_ERR(vma);